Study Of Ocular Biological Parameters Changes At Different Accommodation In Myopic And Non-myopic Children

Objective:This study aimed to investigate the differences in accommodation-induced ocular biometric changes between myopia and non-myopia of school-age children,and to explore the relationship between children’s accommodation at near work and development of myopia.Methods: Twenty myopia school-age children(male 10,female 10,mean age 11.4±0.94 years,equivalent spherical refraction-1.55±0.77D)and fourteen non-myopic school-age children(male 5,female 9,mean age 10.57±1.284 years,equivalent spherical refraction 0.45±0.45D)were recruited for the study.The left eye is setting as the test eye.A range of ocular biometric measurements were captured before and after mydriasis,and during brief accommodation tasks(0,3 and 6 D)using a Badal optical systems built and installed in front of non-contact optical biometric instruments(Zeiss IOL Master 700 and TOMEY CASIA2).The average axial length(AL),anterior chamber depth(ACD),lens thickness(LT),anterior segment length(ASL),vitreous chamber depth(VCD),central corneal thickness(CCT),front radius(FR),and back radius(BR)were determined for each accommodation states,before and after mydriasis.The results were divided into two groups for analysis: group one’s ocular biometric measurements is during brief accommodation tasks(0,3 and 6 D),and group two’s ocular biometric measurements is before and after mydriasis,a 0D accommodation stimulus.A series of linear mixed model(LMM)analyses were carried out for each biometric parameter(AL,CCT,ACD,LT,ASL,VCD,FR and BR)with fixed factors of accommodation stimulus(0,3 and 6 D)or eye states(mydriasis,mydriasis and 0 d accommodation stimuli)and refractive error group(myopia and non-myopia)and their interaction,as well as the confounding factor(gender and age).Repetitive measure analysis of variance(ANOVA)was used to analyze the differences between the two groups in different conditions.Independent-samples T test was used to analyze the differences between the two groups at the same conditions of different refractive error groups.Pearson correlation analysis was used to explore the correlation between each parameter.Paired T test was used to analyze the difference before and after adding spectroscope.Results : At 0,3 and 6D accommodation stimuli,myopic and non-myopic children’s axial length changed significantly during accommodation(P < 0.001).Non-myopic children were increased by 0.016±0.012 mm and 0.032±0.025 mm at the 3D and 6D accommodation stimuli respectively,and myopic children were increased by 0.015±0.019 mm and 0.031±0.027 mm at the 3D and 6D accommodation stimuli respectively.There was no significant difference in axial elongation between myopic and non-myopic children(P=0.968).With the enhancement of accommodation stimuli,the ACD,LT,FR and BR were decreased significantly,LT increased significantly.The changes of ACD,LT and FR in non-myopic eyes were significantly higher than those in myopic eyes(P < 0.05).For the changes of CCT and VCD have no significant difference.After mydriasis,the average AL of myopic children and non-myopic children are22.93±0.498 mm and 24.35±0.708 mm,the difference between the two groups is statistically significant(P < 0.001).Only at 0D accommodation stimuli,the AL of myopia children was significantly longer than that of mydriasis(P=0.03),and there is no difference in AL in other states.Except for BR(P=0.706),the changes of other biological parameters in small pupil and0 D were statistically significant compared with those in after mydriasis(P<0.05).The changes of LT and FR in non-myopic children were significantly higher than those in myopic eyes(P <0.05).The changes of LT,ASL,VCD and CCT in myopia children at small pupil were more significantly higher than those at 0D accommodation stimuli(P < 0.001).There is no significant difference in other parameters(P>0.05).Conclusion:During accommodation tasks,myopic and non-myopic children’s axial elongation were increases significantly with the enhancement of accommodation stimulus,but there is no significant difference between myopic and non-myopic children.With the enhancement of accommodation stimuli,the ACD,LT,FR and BR were decreased significantly,LT increased significantly.The changes of ACD,LT and FR in non-myopic eyes were significantly higher than those in myopic eyes.